It is known to rprovide hydrants with raisable and lowerable sprinklers in an irrigating network of such sprinklers which are supplied by a distribution network and which induce sequential operation of the hydrants. All of these sprinklers are retracted simultaneously.
These systems have been found to be sensitive to working of the ground, e.g. by machinery, either resulting in damage to the system or to hydraulic impact upon the hydrants. This may result in disruption of the sequential operation.
In another system, all of the hydrants are raised so that the sprinkler supports lie above the ground and cultivation is impeded.